Electrostatic dielectric heating apparatus



G. P.. DAlG ER ELECTROSTATIC DIELECTRIC HEATING APPARATUS Aug. 26, 1952 5 Sheets-Sheet 1 Filed Jan. 17, 1947 George R Daiger .3 w i m W3 2 u 6 :1: w L F var s0 ATTORNEY.

Aug. 26, 1952 G. P. DAIGER ELECTROSTATIC DIELECTRIC HEATING APPARATUS Filed Jan. 17, 1947 3 Sheets-Sheet 2 rl l v 'INVENTOR. George RDai er,

. BY M 5. ATTORNEY.

Aug. 26,1952 G. P. DAIGER ELECTROSTATIC DIELECTRIC HEATING APPARATUS Filed Jan. 17, 1947 3 Sheets-Sheet 3 UW v/l/KZr/dw/f/7/67l/Z .NVENTOR. George R Daiger ATTORNEY.

Patented Aug. 26, 1952 George P. Daiger, Canton, Ohio, assigiior to The Hoover Company, North Ganton, Ghio; a, corporation of Ohio Application January 17, 1947, serial N6; 722,559

The present invention relates to a heating apparatus and more particularly to the type operparatus. Another object is to provide a high frequency heating apparatus wherein the electrodes are adjustable relative to the material to be heated. Still another object is to provide a high frequency cooking apparatus which not only sears the exterior areas of meat, but also cooks the meat. Further objects and advantags of the invention will be apparent from the following specification and drawings, wherein:

Figure 1 is a side elevational View partly in section of one embodiment of the invention;

Figure 2 is a top plan view of Figure 1;

Figure 3 is a section along the line 33 of Figure, 2;

Figure Figure 1; a

Figure 5 is a view of the means for locking one of the electrodes, the means being shown in unlocked position;

Figure 6 is a sectional view of another embodiment of the inventio showing electrodes having induction coils;

Figure 7 is a section along the line l'l of Figure 6; and

Figure 8 is an enlarged sectional view'showing the electrical connection to the induction coil.

The embodiment of the invention disclosed in Figures'l to 5 comprises a heatingapparatus provided with a base 16 in which is disposed an un shown high frequency oscillator 15 of a type well known in the art to supply electric current having a frequency range, for example, from one'to fifteen megacycles, and supported on the base 16 is a frame (I of electric insula'ting'material for supporting heating electrodes. The frame I! includes a rectangular bottom wall l8, a rearwall l9 provided at its opposite corners with two projecting arms 20, and spaced from the latter at the opposite corners of the bottom'wall l8 are cornerposts 2| and 22 which are spaced apart to permit passage of a cooking vessel 23 supported on the bottom wall l8. The cooking vessel 23 is transparent so that the operator can observe the cooking of the meat 24 in the vessel 23.

4 is a section along the line 4-4 of I A pair of spaced bosses" 25 project upwardly from the top of the rear walll9 and in eachis a pin 26 which extends intoarms 2'! On a cover 28 to pivot the latteron the'r'ear wall l'9.- The co ver' 28 is of electric insulating" material and when in closed position, as shown in Figure 1, rests uponthe cornerposts 2i and 22. In order to support the cover 28 in an open position as partly shown in dotted lines in Figure l, the cover 28 and t'h'e" rear wall I9 areprovidedrespectively with abutriients 3D and 3| which are in engagement when the cover 23 is moved to its open position.

Supported on the cover 28 are arear electrode 34 and a front electrode 35; each of which is provided along one surface with a metal plate 36 and the opposite surface with a high loss dielectric 31 The electrodes 34 and 35 define a heating area thereb'etween' for the meat 24. The rear electrode 34' is' attached to the cover 28 by three spaced metal brackets 38 rotatably mount ed on a rod 39 rigidly supported in a pair of clamps 40 secured by screws 4|; to the underside of the cover 28. Eachbracket 33 is rigidly fastened, as bywelding, to a spring metal clip 42 extending the full width of the electrode 3 fordetachably securing thereto the rear electrode 34 so that the latter can be removed and cleaned; Rotatablys'u'pporting the brackets 38 with re'spectto the rod 39 permits the rear'elec trode 34 to remain substantially vertical durin opening and closing of the cover 28.

In order to rigidly lock the'rear electrode 34 with respect to the cover 28, the rod 39 is pro vided with a slot 44 which is in alignment with anopening 45 in the center bracket 38 when the cover 28 is closed. A' plunger 46 is reciprocally mounted in three brackets 4'! attached to the cover 28, and one end All of the plungerenters the opening 45 and the slot 44 when the cover is closed and rigidly locks the rear electrode 34 and prevents opening of thecover 28. The plunger 46' is operated by a toggle lever 58 pivotally mounted on" the cover 23 by a rod 5|, and one end of the lever 50' is provided with a pin 52 which'engages an-ofiset recess 53 in the plunger 43th reciprocate the latter'whe'n the lever 50 is operated. A spring 54 is disposed about the plunger it and urges the latter'to its electrode locking position. The upper surface of the cover 28 is recessed at'55'to receive the exterior portion 56 of the lever 50 when the latter is in locked position, and a casing 51 encloses the locking devicebeneath the cover 28 and is provided at its opposite ends with an opening 58 for passage therethrough of the plunger 46 in spaced relation.

The front electrode 35 is supported on the cover 28 by an elongated bracket 60 havin spring metal fingers 6i spaced below the casing 51 for removably securing the electrode thereto. Projecting, upwardly from the bracket '50 is a pair of threaded lugs 62 which extend through an elongated opening 63 in the cover 28 to a slidable cover 64 and the threaded lugs are attached to the slidable cover by insulatedknobs 65.

the rear electrode 34 to vary the space therebetween, depending upon the sizeof the meat '24. to be cooked, and the slidable covers 64 close the openings 63 in all adjusted positionsof the. electrode 35. A spring 66 is disposed about one end portion 61 of an elongated rod 68 which extends through one of the openings 63 and a similar springfie is arranged about a rod 10 spanning the other opening 63, and the springs =66 and 69 at all times urge the electrode 35 toward the rear electrode 34 and the meat 24.

Electric current is supplied to the rear. electrode 34- by a conductor 12 extending from the high frequency oscillator through an elongated opening 13 in the rear frame Wall l9 to an arcuate contact 14, and slidable relative there to is'another contact 15 forming part of a bar is embedded in the cover 28 and is connected at itsforward end 17 to one of the brackets 38, which in turn is connected throughthe spring clamps 42 to-the metal plate 36 of the rear electrode 34. 'The front electrode 35 is connected to By grasping the knobs 65 the front-elec-rfi trode 35 may be moved toward and away from' When the cover 28 is closed the contacts 14-15 and 8l-82 are closed to connect the high frequency oscillator [5 with the electrodes 34 and 35, respectively, and the high frequency oscillator is adjusted to the proper frequency best suited to cook the meat. Upon the application of high frequency current to the electrodes 34 and 35, the

-meat 24 acts as a dielectric and is heated uniformly throughout its mass by the electrostatic field between the electrodes. The dielectric members 31 on each of the electrodes 34 and 35 are of high lossdielectric material in comparison to the meat 24, and they provide a concentrated temthe high frequency oscillator l5 by a conductor 19 extending upwardly through an elongated opening 80 in the rear frame wall l9 to an arcuate contact 8|,and slidable-relative thereto'is a-ccntact 82 forming partof the elongated rod '68 embedded in the cover 28 electrically connected'at its opposite end to one of the projecting lugs 62 by a clamp 83 and then through the spring fingers 6| to the metal plate 36.0f the front electrode 35. p

In operation when the cover 28 .is open as shown in dotted linesin Figure 1, contacts 14-15 and -8l-B2 are out of engagement, the front electrode 35 projects normal to the cover 28 and therear'electrode 34 is substantially. parallel to the cover-28 due to its free pivotal connection in the three brackets 38,- and the lever isin its unlocked position. The meat 24 is placed in the'vessel 23 and the latter inserted between the front cornerposts 2| and-22 of the frame I! into the positionshown inFigure 1. Upon closing the cover28 the rear. electrode 34 drops vertically between the meat 24 and the rear wall 84 of the cooking vessel 23, while the front electrode 35 passes between-the meat 24 and the front wall 85 of the vessel 23. When. the cover is closed the lever 50 is moved to its locked positionwhereby the end48 of the plunger 46 enters the opening hiandthe slot 44 to rigidly lock the rear electrode 34 with respect tothe cover 28 and the meat 24, and also to prevent opening of the cover 28 unless the lever 50 is moved to its unlocked position. The springs 66 and 69 automatically move the front electrode 35 into engagement with the meat 24 and the operator may grasp the knobs 65 to assist in positioning the front electrode 35, the meat 24, and the rear electrode 34 relatively to each other with the high loss dielectric surfaces 31-3! in contact with the meat.

perature higher than that supplied by the electrostatic field. and thus function to supply a high temperatureforsurface cooking to sear the adjacent surfaces of the meat 24.

'When the meat has been cooked the operator moves the lever 50 to its unlocked position, shown in Figure 5, and opens the cover 28 to the dotted line position, shown in Figure l, to disconnect the high frequency. current and permit removal of the cookingvessel 23., If desired the electrodes 34 and.,35 may be removed from their spring clamps 42 and 6| and cleaned. y

- Another embodiment ofthe invention is disclosed insFigures 6 to Sand is similar to the construction previously described with the exception of the electrodes. In this modification of the invention the front and rear electrodes 93 and 9| are each providedalongone surface with a metal plate 92'and on the opposite surface with insulation 33 in whichis embedded a spiral-shaped inductioncoil 94supplied with current from the high. frequency oscillator I5. One .end 35 of the induction coil 94 is connected to the metal plate 92 and the opposite end 35 is connected to a cupshaped metal contact Qlembedded in the insulation.. -To provide an electrical connection between the induction coils 94, an expansible helical wire 38 is supplied at its opposite ends with a plug 95 whichisremovabiy insertedin the cup-shaped contacts .91, and an. expansible insulation I00 covers the wire 98 so that the front electrode can be properly adjusted with respect to the rear electrode 9| and the meat 24.

When it is desired to cook the meat, the electrodes 90 and 9| are adjusted with respect to each other. and. the meat in the same manner as described in the first embodiment. Theinduction coil 94 on each of the high frequency electrodes 90 and 9l heats the metal plates 92 by induction and provides a higher temperature in the metal plates than supplied by the high frequency oscillator IE to provide a high temperature for surface cooking to sear the meat 24.

I claim: a

- liAnfapparatus for electrically heating an article comprising, a framesupporting the article tobe heated, a'cover movably mounted on said frame, an electrode. depending from said cover, and means mounting an extreme end of said electrode on said cover to depend said electrode into said frame for free pivotal movement with respect to said cover within said frame in one directional plane when said cover is moved to opened and closed positions with respect to said frame.

2. An apparatus for electrically heating an article comprising, a frame supporting the article to be heated, a cover movably mounted on said frame, an electrode, means mounting an extreme end of said electrode on said cover to depend said electrode into said frame for free pivotal movement with respectlto said cover within said frame in one directional plane when said cover is moved to opened and closed positions with respect to said frame, and cooperating locking means on said cover and electrode operable when said cover is closed to rigidly lock said electrode with respect to said cover and in said plane.

3. An apparatus for electrically heating an article comprising, a frame supporting the article to be heated, a cover movably mounted on said frame, a pair of electrodes, means on said cover and one of said electrodes mounting the latter on said cover for free pivotal movement with respect to said cover when the latter is moved to opened and closed positions, and means On said cover and the other of said electrodes displaceably mounting the latter on said cover for bodily movement with respect to said one electrode and the article to be heated.

4. Apparatus for heating food comprising: spaced electrodes adapted to receive therebetween the food to be heated, supporting means movably mounted with respect to the food, means pivotally connecting one electrode on said supporting means for pivotal movement with respect to said supporting means when the latter is moved with respect to the food, means diplaceably connecting another electrode on said movable supporting means for relative movement with respect to said one electrode to accommodate the food therebetween, means for locking one of said electrodes with respect to said supporting means, and means for carrying current to said electrodes to heat the food therebetween.

5. Apparatus for heating material comprising: a pair of electrodes adapted to be connected to a source of high frequency potential to produce a high frequency electrostatic field therebetween, means supporting said electrodes in spaced relation to receive the material therebetween, and magnetic means of pancake section connected to said electrodes and disposed against a side of said electrodes and carried thereby to heat said electrodes, whereby said electrodes are heated by said magnetic means to provide a higher localized heat to the material than produced by said electrostatic field.

6. Apparatus for heating material comprising: a frame supporting the material to be heated, a

cover for the material, a pivotal connection between said cover and frame for movement of said cover to opened and closed positions with respect to the material, a pair of spaced electrodes carried by said cover and moved therewith for arrangement about the material when said cover is moved to said closed position, and electrical contacts at said pivotal connection con trolled by movement of said cover to connect and disconnect said electrodes from a source of current when said cover is moved to closed and opened positions with respect to the material. GEORGE P. DAIGER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,572,873 Allcutt Feb. 16, 1926 1,782,069 Henning Nov. 18, 1930 1,797,457 Weiss Mar. 24, 1931 1,806,729 Aitken May 25, 1931 1,873,053 Shaw Aug. 23, 1932 1,921,047 Sword Aug. 8, 1933 1,927,316 Katzman Sept. 19, 1933 1,981,632 Northrup Nov. 20, 1934 2,003,625 Boyer June 4, 1935 2,088,604 Littlefield Au 3, 1937 2,280,771 Dufour et a1. Apr. 28, 1942 2,388,824 Brown Nov. 13, 1945 2,397,615 Mittelmann Apr. 2, 1946 2,401,991 Walton et al. June 11, 1946 2,413,003 Sherman Dec. 24, 1946 2,442,451 Albin June 1, 1948 2,463,054 Quayle et a1 Mar. 1, 1949 2,497,665 Gravley Feb. 14, 1950 FOREIGN PATENTS Number Country Date 517,798 Great Britain Dec. 8, 1940 OTHER REFERENCES Dielectric Heater Unit, Product Engineering, Aug. 1945, page 526.

Electronic Engineering, August 1945, page 633, 

